Nitric oxide, a product of the inducible form of nitric oxide synthase (Inos), has been implicated in the pathogenesis of various forms of inflammation. The current application proposes to evaluate the effectiveness of two mercaptoethylguanidine compounds, mercaptoethylguanidine (MEG) and its dimeric form guanidinoethyldisulfide (GED), as potential therapeutic agents in the treatment of ocular inflammatory disorders. Both MEG and GED are reported to act as iNOS inhibitors and to have additional property of peroxynitrite scavenger activity. The investigators propose to perform preclinical studies testing the efficacy of both compounds in their ability to slow down or reverse the onset of inflammation in a rat model of endotoxin-induced uveitis (EIU) and to perform safety and toxicity studies to determine their therapeutic potential in the treatment of disorders of ocular inflammation. PROPOSED COMMERCIAL APPLICATION: The present study will determine the potential ability of mercaptoalkylguanidine in the treatment of inflammatory eye diseases.